An electro-deposited copper foil is widely used as the base material of a printed wiring board because metal copper is good in electric conductivity, is relatively cheap, and is easy in handling also. The so-called downsizing, such as miniaturization and weight reduction, is required for electronic and electrical equipment in which plenty of printed wiring boards are used. Conventionally, in order to perform such downsizing of electronic and electrical equipment, wiring having a pitch as fine as possible has been required for a signal circuit. Therefore, manufacturers have achieved this by using a thinner copper foil to reduce the time for over-etching in forming wiring by etching to improve the etching factor of wiring formed.
Higher function is also simultaneously required for electronic and electrical equipment miniaturized and weight-reduced. Therefore, sharing of a parts mounting area as large as possible in a limited surface area of the substrate is required with the spreading of the surface mounting method for parts mounting. To achieve the subject, high density printed wiring board performed through a good etching factor has been required. For such a purpose, a lower-profile electro-deposited copper foil than that used for the conventional printed wiring board has been required particularly for a tape automated bonding (TAB) substrate and a chip on film (COF) substrate that are the so-called interposer substrates on which an IC chip and the like are directly mounted. By the way, the grade of profile is defined as the value of the surface roughness (Rzjis) of the bonding surface of a copper foil to be bonded with an insulation layer-forming material, measured in the TD direction according to JIS B 0601-2001, in a standard for copper foils for printed wiring boards. Low profile means that the surface roughness (Rzjis) of the bonding surface is small.
To achieve such objects, Patent Document 1 discloses a surface-treated electro-deposited copper foil characterized in that roughening treatment on a bonding surface is provided on the deposit side of a foil, in which the surface roughness Rz of the deposit side of a drum foil is equal to or smaller than the surface roughness Rz of the shiny side of the drum foil. For the manufacturing of the drum foil, an electrolytic solution, to which a compound having a mercapto group, a chloride ion, and a low molecular weight glue having a molecular weight of 10000 or less and a high molecule polysaccharides are added, is used. Specifically, it is described that the compound having a mercapto group is 3-mercapto 1-propanesulfonate, that the molecular weight of the low molecular weight glue is 3000 or less, and that the high molecule polysaccharide is hydroxyethylcellulose.
Patent Document 2 discloses a method for manufacturing an electro-deposited copper foil by the electrolysis of a sulfuric acid base copper plating solution, characterized by using a sulfuric acid base copper plating solution containing a copolymer of diallyldialkylammonium salt and sulfur dioxide. It is described that the sulfuric acid base copper plating solution preferably contains polyethylene glycol, chlorine, and 3-mercapto-1-sulfonic acid. It is described that the roughness of the deposit side, which is a laminate surface (a bonding surface) to be bonded to an insulating substrate, is small, and that for an electro-deposited copper foil having a thickness of 10 μm, a low profile with a 10-point average roughness Rz of about 1.0 μm±0.5 μm is obtained.
When an electro-deposited copper foil is manufactured using these manufacturing methods, a deposit side having a low profile is surely formed, and the electro-deposited copper foil has sufficient performance as a conventional low-profile electro-deposited copper foil.
[Patent Document 1] Japanese Patent Laid-Open No. 9-143785
[Patent Document 2] Japanese Patent Laid-Open No. 2004-35918
However, the clock frequency of a personal computer, representative of electronic and electrical equipment, is increasing drastically, and the operation speed increases also. In addition, usage of PC is not limited to just data processing, which is the original role as a conventional computer, and there are many choices where the computer itself is used similar with the AV equipment. In other words, not only a music playing function, but also a DVD recording and playing function, a TV receiving and recording function, a videophone function, and the like are equipped one after another.
From the above background, image quality sufficient for watching long hours when the image of a movie and the like is displayed is required for the monitor of a personal computer also, rather than just a data monitor. Further, it is also required to supply monitors at low cost and in a large amount. A liquid crystal display is frequently used for the monitor at present, and in mounting the driver device of the liquid crystal panel, the TAB substrate and the COF substrate are generally used. Therefore, when the high definition and the like of the monitor should be performed, the formation of finer wiring is also required for the wiring board for the driver. When evaluation on 20 μm pitch wiring is carried out, even the electro-deposited copper foil manufactured by the prior art has low profile performance with excellent surface roughness, defects due to large waviness on the edge of wiring tends to occur in the formed fine pattern wiring. Also, problems may occur in use for the electromagnetic shield for a plasma display panel where the formation of the same level of wiring is required. For example, the resolution of the screen and the like do not satisfy the designed values, if the width of the wiring was not obtained as designed.
As described above, for a surface-treated electro-deposited copper foil for use of a printed wiring board and the like, not only to be just a conventional low profile surface-treated electro-deposited copper foil but also to be a surface-treated electro-deposited copper foil having good fine pattern forming performance has been strongly required.